Southern California -- this just in

Heavy rain forces flood advisory in Los Angeles Basin and valleys

Heavy rain swept into the Los Angeles area before dawn Saturday morning, causing the National Weather Service to issue a flood advisory for the L.A. Basin and the San Fernando and San Gabriel valleys.

The National Weather Service said treacherous driving conditions caused hydroplaning on the 405 Freeway Saturday morning, and that urban flooding was expected through L.A. County through to 6:30 a.m. Flooding was also reported on the 110 and 91 freeways. Forecasters warned of “nuisance debris flows” in the burn areas.

Rain was falling as fast as one-tenth to one-quarter of an inch an hour in some areas, forecasters said.

The flood advisory, effective until 6:30 a.m., covered much of the region, from Sunland-Tujunga and Lake View Terrace to La Crescenta, La Canada Flintridge, Monterey Park, Sierra Madre, Diamond Bar, Acton, Long Beach and downtown Los Angeles. A flood advisory means that residents can expect ponding of water in urban areas.

A large band of showers was expected to move eastward out of the L.A. area later this morning.

As of 5 a.m., Santa Barbara has received most of the overnight rain, reporting 1.14 inches, while Ventura County was close behind, with Ventura reporting 0.93 inches of rain and Oxnard 0.69 inches. Los Angeles International Airport recorded one-quarter of an inch of rain, and Burbank, one-fifth of an inch.

[Updated at 6:40 a.m.: Radar shows precipitation moving east into the eastern San Gabriel and Pomona valleys and into San Bernardino County. Forecasters expect the cold, wet conditions to move out of the region Saturday night, and warmer weather to return next week. High pressure should bring temperatures in the valleys back into the 90s on Monday, forecasters said.

This October has seen nine days of rain, a new record for downtown Los Angeles since weather records began being kept in 1877. The previous record of eight days of rain in downtown Los Angeles during the month of October was in 1907.]

-- Rong-Gong Lin II

Photo: A lone cyclist peddles on Santa Fe Dam as sunlight breaks through clouds after an early morning rain in Irwindale. Credit: Irfan Khan / Los Angeles Times